After seeing an M2 in person, I loved the blue stitching throughout the car. I decided to replicate it as close as I could without actually taking out all of the thread and replacing it. Note that my only real sewing experience is 7th grade Home Ec class.
Good news: It's easy and it only cost $5 for the materials from your local sewing shop (I got mine at Michael's)
Bad news: It takes a
long time
I'd recommend starting with a rear headrest, as you can easily take it out of the car to somewhere comfortable with good light.
BE PATIENT! This takes a long time to complete, don't get flustered and ruin your work.
1. Materials:
-Curved needle (The curved needles are extremely useful, so much easier than a normal needle would be.)
-Thread (Pick whatever color you want. The M2 uses a lighter blue, and my car is Estoril Blue, so it worked out for me.)
-Fingernail clippers or small scissors or something similar
2. Measure off a piece of thread that is approximately 6" longer than
twice the length of the section you're working on. Just make sure it is longer than you need: it's a lot easier to cut off extra than to have to combine two sections together.
3. Thread this piece through the needle and tie a knot at the end of it.
4. Find the first portion of thread that is on the top part of stitching and put the needle under as much of the original thread of possible without stabbing your seat (this is where the curved needle comes in handy.)
5. Pull the thread all the way through and pull it taut. Don't pull too hard though or the knot will come out from under the original thread.
6. Continue down the line, being sure to not tangle the needle through the excess thread. Also, keep going the same way (don't switch from top down to bottom up, or it will look a little odd). I found that you can do anywhere from 3 to 5 loops before pulling the whole thing taut. Beyond that, I think you risk ripping the new thread.
7. When you get to the end of the line, just loop under the same original thread 2 or 3 times and pull tight (I could never tie a knot close enough to get it to work). Cut off the excess with your nail clippers or scissors. In the picture, one side I did well and the other side I had to make a new knot and do a couple more loops because I cut it too short, that's why it's bigger compared to the other.
8. Now do the other string and you're done!
Here is what I've done so far. I'll add more pictures as I finish up the steering wheel, back seats divider, and the passenger seat.
Good luck! Most importantly: BE PATIENT!